Lorentz Contraction of Bound States in 1+1 Dimensional Gauge Theory

Abstract

We consider the Lorentz contraction of a fermion-antifermion bound state in 1+1 dimensional QED. In 1+1 dimensions the absence of physical, propagating photons allows us to explicitly solve the weak coupling limit \alpha << m^2 of the Bethe-Salpeter bound state equation in any Lorentz frame. In a time-ordered formalism it is seen that all pair production is suppressed in this limit. The wave function is shown to contract while the mass spectrum is invariant under boosts.

Comments: 12 pages, 5 figures; v2: text shortened, some comments added, references updated, version to appear in Phys Rev D